1. Field of the Invention
This invention relates to the extraction of organic solvents and contaminants from an aqueous media and, more particularly, to a method for recovering the contaminants and the organic solvents used to extract the contaminants from an aqueous solution including soap liquors.
2. Description of the Prior Art
Contaminated soil is becoming a more common environmental problem. The contaminants can include heavy metals, radioactive species, and organics. Various techniques have been developed to remove specific contaminants. As an example, soap liquors can be added to the contaminated soil to solubilize contaminants which are normally insoluble in water. After solubilizing the contaminants, the solution containing the contaminants, the soap liquors, water, and soil fines is removed from the soil, thereby washing the contaminants from the soil.
An analysis of the aqueous solution removed from the soil can be used for treatability studies and for determining the quantity and type of contaminants removed by the soap liquors from the soil. The analysis, in conjunction with soil analysis, can be used for determining if the desired amount of contaminants has been removed from the contaminated soil. To provide this analysis, the solution must be compatible with the instrumentation used to perform the analysis. As an example, because a gas chromatograph, used to identify and quantify contaminants, is not compatible with soap liquors, the contaminants must be separated from the soap liquors prior to performance of the analysis.
Besides separating the contaminants from the soap liquors for enabling an analysis to be performed, it is also desirable to remove the contaminants from the aqueous solution for reducing the volume of he contaminated material for disposal or further processing of the contaminants.
One procedure for removing the solubilized contaminants from the solution is to extract the contaminants from the aqueous solution with an organic solvent. It is also desirable to recover the organic solvent from the solution including the soap liquors for recycling the organic solvent.
There are several extraction techniques for extracting contaminants and organic solvents from solution. One such technique is a continuous liquid-liquid extraction technique which utilizes a continuous extraction device. However, the extraction time of a typical quantity of solution, such as one liter, using the continuous extractor may be 24 to 48 hours.
Another technique for extracting the contaminants and organic solvents from a solution is the separatory funnel liquid-liquid extraction technique. As described in the EPA laboratory manual SW-846, Test Methods for Evaluating Solid Waste, Volume 1B, Revision 1, November 1990, pages 3510A-1 to 3510A-8, a separatory funnel extractor utilizes methylene chloride to extract water insoluble and slightly water soluble organics. However, an emulsion may form, which results in poor recovery of the organic solvents and the contaminants. If the emulsion formation cannot be separated, which occurs when surfactants are present, then the continuous extraction technique is used to extract the solution.
Therefore, what is needed is an improved extraction technique which allows efficient use of a separatory funnel for recovering organic solvents and contaminants from a solution containing a high concentration of surfactants.